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Precision calibration of calorimeter electronics in the D0 liquid argon/uranium particle detector (open access)

Precision calibration of calorimeter electronics in the D0 liquid argon/uranium particle detector

The ability to cross calibrate thousands of channels of detector electronics is of prime importance. This paper will describe the system used to deliver and distribute a 300 nanosecond pulse across 50,000 channels of electronics with better than 0.25% difference between channels from a location more than 200 feet away. The system is used for both cross calibration and functionality checking, (i.e., missing channels). Design of a fixed width pulse generator of high stability is presented as a key ingredient in the system's overall performance. In addition, the design of a controlled impedance distribution system is discussed. 2 refs.
Date: December 1, 1991
Creator: Huffman, D.L.
System: The UNT Digital Library
Mechanical design and development of a high power target system for the SLC Positron Source (open access)

Mechanical design and development of a high power target system for the SLC Positron Source

In order to bring the SLC Positron Source luminosity up to design specifications, the previous (stationary) positron target had to be replaced with a version which could reliably dissipate the higher power levels and cyclic pulsed thermal stresses of the high intensity 33GeV electron beam. In addition to this basic requirement, the new target system had to meet SLAC's specifications for Ultra High Vacuum, be remotely controllable, radiation hard,'' and designed in such a way that it could be removed and replaced quickly and easily with minimum personnel exposure to radiation. It was also desirable to integrate the target and collection components into a compact, easily manufacturable, and easily maintainable module. This paper briefly summarize the mechanical design and development of the new modular target system, its associated controls and software, alignment, and the quick removal system. Operational experience gained with the new system over the first running cycle is also summarized.
Date: December 1, 1991
Creator: Reuter, E.; Mansour, D.; Porter, T.; Sax, W. & Szumillo, A.
System: The UNT Digital Library
A survey of potential low-cost concentrator concepts for use in low-temperature water detoxification (open access)

A survey of potential low-cost concentrator concepts for use in low-temperature water detoxification

Several different concentrator concepts have been considered for use in the detoxification of chemically contaminated water. The reactions of interest are predominantly photocatalytic in nature and are driven by low concentrations (between 1 and 50 suns) of UV radiation in the 300- to 385-nm wavelength range. Optical performance characteristics of these concentrators are thus somewhat different compared to concentrators developed for industrial process heat and electrical energy production. Relaxed optical tolerances might lead to reductions in concentrator cost that, when integrated into overall field system cost, could make the solar-driven process competitive with current UV lamp technology. Aspects of the concentrator system that might realize cost reductions include the concentrating element, the support structure, the tracking and drive system, the manufacturing processes, and the installation procedures. Several ideals have been resurrected from earlier research in the Solar Thermal Program where the need for more stringent optical performance requirements led to a decline or even an end to further investigation. In light of this new application, the most promising of these ideas are presented, including a description and a discussion of the cost and performance trade-offs. In addition, the results of recent investigate research on several of these concepts will be …
Date: December 1, 1991
Creator: Wendelin, T.
System: The UNT Digital Library
Lessons from the SLC for future LC control systems (open access)

Lessons from the SLC for future LC control systems

The SLC control system is the dynamic result of a number of forces. The most obvious force is the functional requirements of the SLC itself, but other forces are history, budget, people, available technology, etc. The plan of this paper is to describe the critical functional requirements of the SLC which caused significant development of the control system. I have tried to focus on functional requirements as a driver, and I will describe some solutions which we have implemented to satisfy those requirements. The important functional requirements drivers for the control system discussed in this paper are: Repetition rate; Sensitivity to orbit distortion; Stability/Automation; and Accelerator Development.
Date: December 1, 1991
Creator: Humphrey, R.
System: The UNT Digital Library
Pion interferometry and resonances in pp and AA collisions (open access)

Pion interferometry and resonances in pp and AA collisions

We study the sensitivity of pion interferometry in {bar p}p and {bar p}p collisions at ISR energies to the resonance abundance. We show that those data are not compatible with the full resonance fractions predicted by the Lund model. The preliminary S+S and O+Au data at 200 GeV are, however, not incompatible with the Lund predictions, although their sensitivity to resonances is significantly weaker than in the pp/{bar p}p case.
Date: December 10, 1991
Creator: Padula, S.S. (Universidade Estadual Paulista, Sao Paulo, SP (Brazil). Inst. de Fisica Teorica) & Gyulassy, M. (Lawrence Berkeley Lab., CA (United States))
System: The UNT Digital Library
Pions in and out of equilibrium (open access)

Pions in and out of equilibrium

Can final state scattering wrestle the secondaries in nucleus-nucleus collisions into a fluid state near local thermal equilibrium What do the pion p{sub T} spectra measured in pp, pA and SPS light ion experiments already tell us about the approach to equilibrium To begin to address these questions, we must face the nonequilibrium nature of hadronic evolution in the late stages of these collisions. I will outline efforts to apply transport theory to the nonequilibrium pion fluid at midrapidity focusing on two phenomena: partial thermalization and pion conservation.
Date: December 1, 1991
Creator: Gavin, S.
System: The UNT Digital Library
Air exchange effectiveness of conventional and task ventilation for offices (open access)

Air exchange effectiveness of conventional and task ventilation for offices

Air quality and comfort complaints within large buildings are often attributed to air distribution problems. We define three air exchange effectiveness parameters related to air distribution. The first two indicate the indoor air flow pattern (i.e., the extent of short circuiting, mixing, or displacement flow) for an entire building or region. The third parameter is most useful for assessments of the spatial variability of ventilation. We also define the air diffusion effectiveness which indicates the air flow pattern within specific rooms or sections of buildings. The results of measurements of these parameters in US office buildings by the authors and other researchers are reviewed. Almost all measurements indicate very limited short circuiting or displacement flow between locations of air supply and removal. However, a moderate degree of short circuiting is evident from a few measurements in rooms with heated supply air. The results of laboratory-based measurements by the authors are consistent with the field data. Our measurements in office buildings do indicate that ventilation rates can vary substantially between indoor locations, probably due to variation in air supply rates between locations rather than variation in the indoor air flow patterns. One possible method of improving air distribution is to employ …
Date: December 1, 1991
Creator: Fisk, W. J.; Faulkner, D. & Prill, R. J.
System: The UNT Digital Library
Momentum density and 2D-ACAR experiments in YBa sub 2 Cu sub 3 O sub 7 (open access)

Momentum density and 2D-ACAR experiments in YBa sub 2 Cu sub 3 O sub 7

We compare measured c-projected 2D-ACAR spectrum from an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7-x} with the corresponding band theory predictions. Many different one-dimensional sections through the spectrum are considered, together with the characteristic amplitudes and shapes of the spectral anisotropies, with a focus on identifying and delineating Fermi surface signatures in the spectra. The positron data clearly show several distinct features of the ridge Fermi surface predicted by the band theory, and give an indication of the pillbox Fermi sheet. The good agreement between theory and experiment suggests that the band theory framework based on the local density approximation (LDA) is capable of providing a substantially correct description of the momentum density and Fermiology of the normal ground state electronic structure of YBa{sub 2}Cu{sub 3}O{sub 7}.
Date: December 1, 1991
Creator: Bansil, A. (Northeastern Univ., Boston, MA (United States). Dept. of Physics) & Smedskjaer, L.C. (Argonne National Lab., IL (United States))
System: The UNT Digital Library
ASME Subsection ISTD recommendations based upon NPAR snubber aging research results (open access)

ASME Subsection ISTD recommendations based upon NPAR snubber aging research results

As a result of information obtained during the US Nuclear Regulatory Commission's (NRC) Nuclear Plant Aging Research(NPAR) Program, Snubber Task research, recommendations are made in the three following areas for the next revision of the American Society of Mechanical Engineers (ASME) Operations and Maintenance (OM) Code, Subsection ISTD: Service-Life Monitoring; Visual Examination Attributes; and Failure Grouping and Corrective Action.
Date: December 1, 1991
Creator: Blahnik, D.E. & Brown, D.P.
System: The UNT Digital Library
Behavior of TPC's in a high particle flux environment (open access)

Behavior of TPC's in a high particle flux environment

TPC's (Time Projection Chamber) used in E-810 at the AGS (Alternating Gradient Synchrotron) were exposed to fluxes equivalent to more than 10{sup 7} minimum ionizing particles per second to find if such high fluxes cause gain changes or distortions of the electric field. Initial results of these and other tests are presented and the consequences for the RHIC (Relativistic Heavy Ion Collider) TPC-based experiments are discussed.
Date: December 13, 1991
Creator: Etkin, A.; Eisemann, S. E.; Foley, K. J.; Hackenburg, R. W.; Longacre, R. S.; Love, W. A. et al.
System: The UNT Digital Library
Backgrounds and masking at the Tau-Charm Factory (open access)

Backgrounds and masking at the Tau-Charm Factory

Preliminary results are presented for beam-related backgrounds in the Tau-Charm Factory detector. The Orsay flat-beam optics design was used in the simulations. Results with different masking schemes are compared for lost beam particle backgrounds.
Date: December 1, 1991
Creator: Stoker, D. P.
System: The UNT Digital Library
Results from CERN experiment NA36 on strangeness production (open access)

Results from CERN experiment NA36 on strangeness production

Measurements of the production of strange particles in the reactions S + Pb and S + S at beam momentum 200GeV/c per nucleon are presented. A short description of CERN experiment NA36 and the methods of raw data analysis, is followed by physics results concentrating on the dependence of strange particle production on multiplicity. Transverse momentum distributions are also presented.
Date: December 1991
Creator: unknown
System: The UNT Digital Library
Recent results on K. omega. and. pi. pi. systems from LASS (open access)

Recent results on K. omega. and. pi. pi. systems from LASS

Preliminary results from ongoing analyses of the K{sup minus}{omega} and the hypercharge exchange produced {pi}{sup minus}{pi}{sup +} systems are presented. The data described are taken from a 4.1 event/nb exposure of the LASS spectrometer to an 11 GeV/cK{sup minus} beam.
Date: December 1, 1991
Creator: Aston, D.; Bienz, T.; Bird, F.; Dunwoodie, W.; Johnson, W.B.; Kunz, P. et al.
System: The UNT Digital Library
Boron Nitride Protective Coating of Beryllium Window Surfaces (open access)

Boron Nitride Protective Coating of Beryllium Window Surfaces

The use of beryllium windows on white synchrotron radiation beamlines is constrained by the fact that the downstream surfaces of these windows should not be exposed to ambient atmosphere. They should, rather, be protected by a tail-piece under vacuum or containing helium atmosphere. This tailpiece is typically capped by Kapton (3M Corporation, St. Paul, MN) or aluminum foil. The reason for such an arrangement is due to the health risk associated with contaminants (BeO) which from on the exposed beryllium window surfaces and due to possible loss of integrity of the windows. Such a tail-piece may, however, add unwanted complications to the beamline in the form of vacuum pumps or helium supplies and their related monitoring systems. The Kapton windows may burn through in the case of high intensity beams and lower energy radiation may be absorbed in the case of aluminum foil windows. A more ideal situation would be to provide a coating for the exposed beryllium window surface, sealing it off from the atmosphere, thus preventing contamination and/or degradation of the window, and eliminating the need for helium or vacuum equipment.
Date: December 1991
Creator: Gmuer, Nicholas F.
System: The UNT Digital Library
Uncertainty of calorimeter measurements at NREL's high flux solar furnace (open access)

Uncertainty of calorimeter measurements at NREL's high flux solar furnace

The uncertainties of the calorimeter and concentration measurements at the High Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL) are discussed. Two calorimeter types have been used to date. One is an array of seven commercially available circular foil calorimeters (gardon or heat flux gages) for primary concentrator peak flux (up to 250 W/cm{sup 2}). The second is a cold-water calorimeter designed and built by the University of Chicago to measure the average exit power of the reflective compound parabolic secondary concentrator used at the HFSF (over 3.3 kW across a 1.6cm{sup {minus}2} exit aperture, corresponding to a flux of about 2 kW/cm{sup 2}). This paper discussed the uncertainties of the calorimeter and pyrheliometer measurements and resulting concentration calculations. The measurement uncertainty analysis is performed according to the ASME/ANSI standard PTC 19.1 (1985). Random and bias errors for each portion of the measurement are analyzed. The results show that as either the power or the flux is reduced, the uncertainties increase. Another calorimeter is being designed for a new, refractive secondary which will use a refractive material to produce a higher average flux (5 kW/cm{sup 2}) than the reflective secondary. The new calorimeter will use a time …
Date: December 1, 1991
Creator: Bingham, C. E.
System: The UNT Digital Library
A multilevel preconditioner for domain decomposition boundary systems (open access)

A multilevel preconditioner for domain decomposition boundary systems

In this note, we consider multilevel preconditioning of the reduced boundary systems which arise in non-overlapping domain decomposition methods. It will be shown that the resulting preconditioned systems have condition numbers which be bounded in the case of multilevel spaces on the whole domain and grow at most proportional to the number of levels in the case of multilevel boundary spaces without multilevel extensions into the interior.
Date: December 11, 1991
Creator: Bramble, J.H.; Pasciak, J.E. & Xu, Jinchao.
System: The UNT Digital Library
Long baseline neutrino experiments with the Fermilab Main Injector (open access)

Long baseline neutrino experiments with the Fermilab Main Injector

This report contains a talk on experiments to detect neutrino oscillations. (LSP)
Date: December 1, 1991
Creator: Bjorken, J. D.
System: The UNT Digital Library
An overview: Challenges in wind technology development (open access)

An overview: Challenges in wind technology development

Developing innovative wind turbine components and advanced turbine configurations is a primary focus for wind technology researchers. In their rush to bring these new components and systems to the marketplace, designers and developers should consider the lessons learned in the wind farms over the past 10 years. Experience has shown that a disciplined design approach is required that realistically accounts for the turbulence-induced loads, unsteady stall loading, and fatigue effects. This paper reviews past experiences and compares current modelling capabilities with experimental measurements in order to identify some of the knowledge gaps that challenge designers of advanced components and systems. 7 refs., 11 figs.
Date: December 1, 1991
Creator: Thresher, R W & Hock, S M
System: The UNT Digital Library
The effect of processing on strength of Nicalon fibers in Nicalon fiber-SiC matrix composites (open access)

The effect of processing on strength of Nicalon fibers in Nicalon fiber-SiC matrix composites

Degradation of strength of Nicalon (silicon carbide) fibers during processing of Nicalon fiber-SiC matrix composites was studied. Strength distribution of as-fabricated Nicalon fibers was obtained via bundle tests. Whereas, strengths of fractured fibers in Nicalon fiber-reinforced SiC matrix composite specimens were estimated by measuring fracture mirror radii. Comparison of fracture probability plots indicate significant differences in the behavior of the as-fabricated fibers and those in the composite. Possible causes leading to these differences are discussed.
Date: December 1, 1991
Creator: Singh, D. & Singh, J.P.
System: The UNT Digital Library
Session summary: Electronics, triggering and data acquisition (open access)

Session summary: Electronics, triggering and data acquisition

The session focused on the requirements for calorimetry at the SSC/LHC. Results on new readout techniques, calibration, radiation hard electronics and semiconductor devices, analog and digital front and electronics, and trigger strategies are presented.
Date: December 1, 1991
Creator: Rescia, S.
System: The UNT Digital Library
Observation of high current effects in high energy linear accelerators (open access)

Observation of high current effects in high energy linear accelerators

The acceleration and transport of electron beams with high currents and low emittances are subjects studied very carefully for many operating accelerators and most future accelerators. For a example, several Free Electron Lasers (FEL) and the Stanford Linear Collider (SLC) presently operate with high energy intense beams. The next generation of synchrotron light sources and future linear colliders require a much higher degree of component precision and beam control. In this note the basic concepts governing the effects of high currents in accelerators are explored, including observations of high currents in present accelerators. The effects of longitudinal wakefields on acceleration and energy spreads are studied first. Then, the transverse equations of motion are developed including the technique of BNS damping to control wakefield growth. These wakefield effects are investigated to characterize their influence on the control and observation of beam oscillations. Finally, the reduction of transverse wakefield effects is important for maintaining the emittance of intense beams. 49 refs., 48 figs.
Date: December 1, 1991
Creator: Seeman, J.T.
System: The UNT Digital Library
Near-term viability of solar heat applications for the federal sector (open access)

Near-term viability of solar heat applications for the federal sector

Solar thermal technologies are capable of providing heat across a wide range of temperatures, making them potentially attractive for meeting energy requirements for industrial process heat applications and institutional heating. The energy savings that could be realized by solar thermal heat are quite large, potentially several quads annually. Although technologies for delivering heat at temperatures above 100{degrees}C currently exit within industry, only a fairly small number of commercial systems have been installed to date. The objective of this paper is to investigate and discuss the prospects for near-term solar heat sales to federal facilities as a mechanism for providing an early market niche to the aid the widespread development and implementation of the technology. The specific technical focus is on mid-temperature (100{degrees}--350{degrees}C) heat demands that could be met with parabolic trough systems. Federal facilities have several relative to private industry that may make them attractive for solar heat applications relative to other sectors. Key features are specific policy mandates for conserving energy, a long-term planning horizon with well-defined decision criteria, and prescribed economic return criteria for conservation and solar investments that are generally less stringent than the investment criteria used by private industry. Federal facilities also have specific difficulties in …
Date: December 1, 1991
Creator: Williams, T.A.
System: The UNT Digital Library
Arms Control past and future (open access)

Arms Control past and future

I am going to talk today about Arms Control. First, I want to go over the recent history of the process. Five years ago, the pace of arms control changed dramatically. From an outsider it probably didn't appear that way -- but those working it, the shift from the historic glacial speed normally associated with this process to one of pressures -- political and economic -- national and global -- to actually conclude meaningful, verifiable agreements was a major change. Then, I want to spend a few minutes covering the future of arms control new that we have lost our enemy, and it is no longer a bipolar world. I also want to leave time for easy questions.
Date: December 1, 1991
Creator: Fox, T.R.
System: The UNT Digital Library
Novel QCD effects in nuclear collisions (open access)

Novel QCD effects in nuclear collisions

Heavy ion collisions can provide a novel environment for testing fundamental dynamical processes in QCD, including minijet formation and interactions, formation zone phenomena, color filtering, coherent co-mover interactions, and new higher twist mechanisms which could account for the observed excess production and anomalous nuclear target dependence of heavy flavor production. The possibility of using light-cone thermodynamics and a corresponding covariant temperature to describe the QCD phases of the nuclear fragmentation region is also briefly discussed.
Date: December 1, 1991
Creator: Brodsky, Stanley J.
System: The UNT Digital Library